A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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There are many process control applications in the industry where it is desirable to have multiple control…
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A fluid is any substance having the ability to flow: to freely change shape and move under the influence of a…
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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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Perhaps the simplest form of solid or liquid level measurement is with a float: a device that rides on the…
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The final step in treating wastewater before releasing it into the natural environment is to kill any harmful…
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A great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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The Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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Control valves are supposed to deliver reliable, repeatable control of process fluid flow rate over a wide…
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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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Valves can experience a number of problems, most of them either preventable or repairable. These problems can…
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This section shows some of the many instrument symbols found in different types of technical diagrams used to…
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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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Calculus has a reputation for being difficult to learn, and with good reason. The traditional approach to…
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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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Flow, by definition, is the passage of material from one location to another over time. So far this chapter…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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Atom: the smallest unit of matter that may be isolated by chemical means. Particle: a part of an atom,…
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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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When I began teaching full-time in 1998, most of what I thought I understood about good teaching was actually…
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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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An important legacy technology for all kinds of continuous measurement is the self-balancing system. A…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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A pressure switch is one detecting the presence of fluid pressure. Pressure switches often use diaphragms or…
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